Three weeks before her rousing Golden Globes speech that had fans speculating whether she would run for president, Oprah Winfrey made it clear that being the commander in chief is not in her future.

“I’ve always felt very secure and confident with myself in knowing what I could do and what I could not. And so it’s not something that interests me,” the 63-year-old former talk show host told InStyle Editor-in-Chief Laura Brown in the cover story for their March Fashion Issue. “I...